Method and apparatus for contacting gaseous fluids with solids



1960 P. J. SCHOENMAKERS 2,935,466

METHOD AND APPARATUS FOR CONTACTING GASEOUS FLUIDS WITH SOLIDS FiledJan. 27, 1956 6 Sheets-Sheet 1 I23 INVENTOR: E 7 AK RS A PIETER JSCHOENM E 4 B W FIG. 5 8 HIS A TORNEY May 3, 1960 P. J. SCHOENMAKERS2,935,455

METHOD AND APPARATUS FOR CONTACTING GASEOUS mums WITH souns Filed Jan.27, 1956 6 Sheets-Sheet 2 INVENTOR:

PIETER J. SCHOENMAKERS ma Mm ms A TORNEY May 3, 1960 P. J. SCHOENMAKERS3 6 METHOD AND APPARATUS FOR CONTACTING GASEOUS FLUIDS WITH SOLIDS FiledJan. 27, 1956 s Sheets-Sheet s INVENTOR PIETER J. SCHOENMAKER? BY WM flW HIS ATTORNEY May 3, 1960 P. J. SCHOENMAKERS 2,935,466

METHOD AND APPARATUS FOR CQNTACTING GASEOUS FLUIDS WITH SOLIDS FiledJan. 27, 1956 6 Sheets-Shegt 4 I NVENTOR PIETER J. SCHOENMAKERS BY msATTORNEY May 3, 1960 P. J. SCHOENMAKERS METHOD AND APPARATUS FORCONTACTING GASEOUS FLUIDS WITH SOLIDS Filed Jan. 27, 1956 WASTE HEATRECOVERY FLUlD-BED-4l 3/ l5 REACTOR QUENCH AIR LIFT POT 6 Sheets-Sheet 5PRODUCT I N VENTOR PIETER J. SCHOENMAKERS HIS ATTORNEY y 1960 P. J.SCHOENMAKERS 2,935,466

METHOD AND APPARATUS FOR CONTACTING GASEOUS FLUIDS WITH SOLIDS FiledJan. 27, 1956 6 Sheets-Sheet 6 FIG. 2| FIG. 22

' INVENTORZ PIETER J. SCHOENMAKERS HIS ATTORNEY METHOD AND APPARATUS ronCONTACTING GASEOUS FLUIDS wrrn SOLIDS Pieter .l'. Schoenmakers, Delft,Netherlands, assiguor to Shell Oil Company, a corporation ofDelawareApplication January 27, 1956,Serial No. 561,881 Claims priority,application Netherlands January 31, 1955 17,.Claims. (Cl. mas-176i Thisinvention relates to a new method and apparatus for the contacting ofgaseous fluids with fiuidizable solids. One aspect of the inventionrelates to a process and ap- "paratus for continuously eflecting a rapidchange in temperature in a gaseous fluid, or the rapid vaporization of avaporizable liquid, by contact with a fluidizable solid of ditferenttemperature. Q

The process of the invention is particularly applicable in the treatmentof gaseous fluids (by which I mean to include true gases, vapors, andalso liquids which are immediately vaporized upon contact under theconditlons) at high temperatures where undesired reactions tend to' ortreatments which proceed and takeplace in less than 0.5 second. Ontheother hand, the process and apparatus of the invention are advantageousfor the rapid cooling of a' vaporous high temperature reaction productwhereby side reactions are repressed and/ or the reaction product isfrozen at or near a high temperature equilibrium state. By applying bothof these simultaneously it is possible to obtain both a very rapidheatingand a very rapid cooling after a very short or relatively longresidence time at the high temperature or in other words a substantiallysquare temperature versus time curve.

In many cases it is desirable or necessary, to contact one or moregaseous fluids with a solid material and in many of these cases theefliciency and duration of such contact are quite important. I

t In the past it has been the usual practice to pass the gaseous fluidthrough a bed of pieces of the solid which Were either in a fixedposition or slowly moved through the contacting zone. In these cases thesolid is in the form of relatively large particles upwards of inch indiameter since otherwise the pressure drop through the bed of particlesbecomes inordinately large.

Also, the so-called fluidized solid technique has come into wide-spreaduse for these purposes. This technique is not applicable for all solidsbut is applicable andoften advantageous when the solid is one which canbe fluidized, i.e. be brought into a fluidized (pseudo liquid) state bysuitable aeration with a gaseous fluid. The first requirement of thesolid in this respect is that it be in powdered form, i.e. have a rangeof particle sizes from a minimum of a fraction of 21. micron up to amiximum of about 2 millimeters mean diameter. Although it is notnecessary that this full range of particle sizes be present it isgenerally necessary that the particles have a substantial range ofsizes, i.e. 'a factor of 3 or more, within these limits. Thesecondrequirement of the solid is that the shape and/or electrical propertiesof the solid particles be such as to allow fluidization. Flake material,needle shaped particles, flocculant precipitates, some powders F atentedMay 3,1960

igcg I 5.2O microns, most magnetic solids, and solids consisting of onlylarge particles, e.g. greater than about 2 millimeters, are diflicult orimpossible to fluidize with. a gaseous fluid. The suitability ofpowdered solids in this 5 respect is best indicated by their angle ofrepose. Thus,

the above named materials, and others which cannotzbe properlyfluidized, have a high angle of repose, e.g. 80 or more for burnt gypsumandtalcum powder. Solids which may befluidized generally'have an angleof repose 1 of 55 or less and the better ones an. angle of repose ofabout 45 or less. 1 a When the above requirements are met the solid maybe fluidized. In the fluidized state the powdered solid acts in manyways like .a true'liquid, e.g. it seeks its own level; it is capable. ofexerting a hydrostatic head; it can be pumped or poured much likeamolten metal.

One of the characteristics of a fluidized powder is its cohesiveness Forexample, in contacting a gaseous fluid with a fluidized solid it iscommon, eg in conventional fluidized catalyst catalytic cracking, topass'thegaseous fluid up through a bed of the fluidized powder at asuperficial gas velocity which is considerably above the free fallvelocity of the particles of the powder as calculated small amount ofthe powder is torn away from the fluidized bed and carried. by theissuing gaseous fluid. For various reasons the individual particles tendto approach or become closely associated with others, as a re-'consisting entirely of'very small particles, e.g. less than sult ofwhich the particles do not behave as individual particles and the massbehaves much like a liquid.

vOn'the other hand, since this cohesive tendency increases withdecreasing particle size (which accounts for the difficulty influidizing powders in which all of the particles are of extremely smalland uniform size, e.g., less than 5 microns, and also large particles)the solid may contain, or even consists mainly of, quite smallparticles, e.g. average V/ S diameter less than 500 microns.

In the past this fluidized state has been obtained by passing a gas, orvapor, or in some cases a liquid which is rapidly vaporized upon contactwith the solid, up through a bed of the powdered solid.

If a gas is introduced into the bottom of a settled bed of fluidizablesolid at very low rate, the gas simply passes through the minuteinterstices and out of the top of the bed without affecting the beditself. If the gas velocity is increased slowly a point is reached atwhich the bed expands somewhat and the particles move about. The pointat which this occursmay be called the minimum .fiuidization gasvelocity. This minimum 'fluidization: gas

fiuidization-gas velocity the bed has usually expanded by approximately12% of its original, i.e. settled, volume. If the gas velocity isfurther increased the bed of powder expands somewhat further with noappreciable increase in pressure drop through the bed until a maximumlimiting velocity is reached above which the powder is blown upward withthe gas. Beyond this point a fluidized state no longer exists and thepowder is simply dispersed as a suspension of individual particles inthe gas. In the region of gas velocities giving a fluidized state thegas passes through the somewhat expanded interstices, although in manycases, due to maldistribution oi the gas, bubbles form and pass upthrough the pseudo liquid powder.

Thus, in the case of fluidized solids, the expansion of the interstices,within the limitations allowing the fluidized state, is produced by theenergy of the gas forced up through the bed of powder. Y

The phenomenon of fluidization of powders has long .been known and thecohesive behavior has been qualitatively recognized. The magnitude ofthis cohesion, however, has, to the best of my knowledge, not beenmeasured nor appreciated.

The present invention is based on the discovery that it is in'many casesadvantageous with astounding .results to pass the gaseous fluid to becontacted horizontally (or approximately so), through a free fallingbody of the fluidized solid. 1

. It has hitherto been proposed to pass various gaseous fluids through afree falling shower of solid material, but in these prior instances theconditions were such that the particles of the solid behaved asindividual or discrete particles. For example, if a fine powder ispassed through a sieve into a free falling space the particles behave asa shower of discrete particles rather widely spaced as, for example, inarain. Passage of a gaseous fluid horizontally through such a'showeraffords only a very mediocre contact efficiencyand if the velocity ofthe gaseous fluid is appreciable, the individual particles are carriedwith the gaseous fluid.

If large particles are allowed to drop through an orifice into a freefalling space, the particles again behave as individual particles andalso give only an open shower, again much like rain, which likewiseaflords only a mediocre contact with a gaseous fluid passed horizontallytherethrough. In the case of large particles this is due mainly to twofactors. The first is that if large particles such as granules, spheres,pellets, etc. which are not fluidized are allowed to flow through anorifice into a free fall space, the mass flow of solid through theorifice does not obey the laws which apply to fluids and is considerablysmaller. Even with orifices withdiameters many times the diameter of theparticles, the resulting shower of particles is loose, non-coherent, andtotally diiferent from the close coherent nature of a fluidized solid.The second factor is the natural tendency of individual free fallinggranules to separate. It is a well known fact of elementary physics offree falling bodies that if two particles are released into a freefalling space, one immediately after the other, the distance betweenthem continues to increase up until the. time where they attain theirmaximum or terminal free fall velocity. This is due to the fact that thedistance of fall is a function of the square of the time of fall. If onepasses a stream of pellets, for example, through an orifice into a freefalling space the pellets separate. However, for the case of fluidizedpowders, within wide limits, this separation does not take place to anyappreciable extent even over a considerable and practical distance offree falling height. This is due to the cohesive nature mentioned and tothe relative low limiting free fall velocities of particles of the smallsize range in question.

There is a distinct difference in the behavior of a free falling mass offluidized solids and free falling discrete particles of either large orsmall size when a gaseous fluid is passed horizontally therethrough. Ifone has an annular orifice and passes through this orifice into a freefalling space powdered solid at such a mass rate that the particles actmore or less as an annular shower of discrete particles, and if a gas ispassed horizontally outward through the free falling annular shower at:1 velocity less than the terminal free fall velocity of the particlesof the powder, the particles tend to move with the gas so that theshower of particles increases considerably in diameter a short distancebelow the orifice giving a cone shaped shower.

In the case of a free falling mass of fluidized powder, on the otherhand, the cohesion mentioned is quite ap parent. The annular sheet doesnot become conical but remains substantially cylindrical even when thehorizontal velocity of the gas passing therethrough approaches theterminal free fall velocity of the individual particles. If the velocityof the gas passing through the sheet is further increased the sheetretains this substantial cylindrical shape until at quite highvelocities of the gas the 4 sheet bulges and then suddenly ruptures intoa number of incoherent masses. In other words, it acts like a liquid.

In the case of a shower of large particles, e.g. above 1 mm. diameter,the spreading into a cone does not occur at'nominal gas velocities duefirstly to the fact that the terminal free fall velocity of the suchlarger particles is much higher than the horizontal gas velocity andhence little angular horizontal displacement results, and secondly tothe fact that due to the above-described separation phenomenon theshower offers practically no resistance to even considerable horizontalflows of gas; in other words, there is only a mediocre contact betweenthe free falling relatively widely separated granules of solids and thegas. If the gas velocity is substantially increased, however, even thesecomparatively large particles behave just as described for discreteparticles of powder. Thus, a conical configuration results and the angleof the cone increases with increasing gas velocity without any ruptureas described above.

In the manner of contacting according to the invention, the effluentgaseous fluid passing through the mass of free falling solid entrains anunexpectedly small amount of this solid at gas velocities below that atwhich the sheet mass is ruptured.

I have found that by passing a gaseous fluid through such a coherentfree falling stream of fluidized powder an unexpectedly excellentcontact can be obtained with an extremely short contact time. Thus, forinstance, I have passed vapors through such a free falling stream offluidized solid of only about 7 millimeters thickness and have therebyincreased the temperature of the vapors from a low temperature to within5 C. of the temperature of the solid in the 900 C. temperature range.This far surpasses any other method known to me for effecting extremelyrapid heating of a gaseous fluid in a continuous manner. 7

According to the invention the gaseous fluid to be contacted is passedhorizontally through a free falling mass of the fluidized solid. As willbe described in more detail below, certain conditions are essential andothers are highly desirable in order to obtain this sort of contact.

Firstly, the solid must be one which meets the abovedescribedrequirements and is therefore fluidizable. One suitable material whichhas been extensivelyused in various studies leading tothe invention andin pilot plant operation in the production of olefins from paraflin wax,is a fine silica sand having the following properties:

Volume/surface mean particle diameter=l microns;

True specific gravity=2.660 g./cc.;

Specific gravity in the fluidized state at minimum fiuidization gasvelocity=l400 kg./m.

Size Distribution Sieve Aperture in Mierous 420 210 177 150 125 PercentWeight Undersize 07. 6 64. 0 30. 2 14. 6 5.0 3. l

ia/E wherein:

=mass velocity in kg./m. sec. C=a proportionality factor 1 p=density ofthe fluidized solid in kg./m. g=gravity acceleration in m./sec. h=depthof fluidized bed above the orifice in meters Thus, the mass flow isproportional to the 0.5 power of the pressure drop and very large massflows may be ob- 7 by about 2 to 10 sheet thicknesses. Such shieldingforces contacted gaseous fluid to flow downward parallel to the sheet.

When the gaseous fluid to be contacted is initially in the form of aforceable liquid which quickly vaporizes on contacting the sheet, it isbest injected at a relatively high point near the top of the sheet asillustrated. However, when the gaseous fluid is initially in vapor formit may be introduced at a plurality of points of different elevation aswell as in the horizontal arrangement illustrated. If the gaseous fluidto be contacted is introduced at a plurality of points, its jet head isless and there is considerably less tendency to rupture the sheet.

The sheet 1 in the apparatus according to Figures" 1 and 2 is formed byflow of fluidized solid through slit 2 provided at the top of the vessel3 which houses the sheet. The fluidized solid is introduced via a pipe 4to the fluidized bed in the upper vessel 5 which bed is maintained inthe pseudo-liquid state by aeration gas supplied via the line 9. Thesolid material comprising the free falling sheet is collected in thecollecting device 6 in which a fluidized bed of the solid is maintained.Aeration gas to maintain this lower fluidized bed in a pseudo-liquidstate is introduced by line 8. In the arrangement illustrated thiscollecting device is integral with the lower part of the vessel 3. Thefluidized solid particles are withdrawn from the collecting device 6 bypipe 7. By altering the level of the fluidized bed in the upper sectionthe mass of fluidized material passing through the slit orifice 2 can beregulated. The gaseous fluid which is to be contacted with the solid issupplied by one or more lines 10, 11, and 12 to one side of the sheet 1.In place of the separate lines a single distributing means extendingover the whole width of the sheet may be used. The gaseous fluid, afterpassing through the sheet, is withdrawn on the other side thereofthrough line 13.

If the sheet consists of material which has a temperature considerablylower than that of the gaseous fluid to be contacted the gaseous fluidis cooled very rapidly on passing through the sheet.

If, on the other hand, the temperature of the sheet is considerablyhigher than the temperature of the gaseous fluid supplied through lines10, 11, and 12, the gaseous fluid is heated very rapidly on passingthrough the sheet. The heated gases being withdrawn byline 13 may bequenched by means of a quenching medium introduced via line 14. a

The described arrangement is quite suitable for many reactions which maybe carried out either thermally or catalytically. For instance, thethermal cracking of paraflin waxes to produce olefins, and the thermalcoking of tars or pitches are examples of treatments for which thissystem is suited. The system may also be used to carry out reactionsbetween two or more gases which have to be raised rapidly to the desiredreaction temperature. Thus, for example, separate reactants may besupplied separately via the lines 10, 11, and 12. The mixture is rapidlyheated to the reaction temperature upon being passed through the sheet 1and the vapors afterwards react in the space downstream with respect tothe sheet 1. The reaction product is removed by line 13 as before. Iftwo separate reactant gases are mixed first and then supplied by lines10, 11, and 12, the reaction is at least initiated and in some cases maybe substantially completed during the exceedingly short time that themixture is passing through the sheet.

a In the arrangement illustrated in Figures 3 and 4 the orifice is anannular slit 15. The fluidized solid particles in the supply means 5flowthrough this annular slit to form a cylindrical sheet 16 in vessel3.

Any closed figure may be chosen for the cross section of the sheet. Thiscross section is preferably a circle (annulus) (as illustrated in Figure4) since in this case the gaseous fluid to be contacted may be moreevenly distributed when introduced centrally via the nozzle 17. If

the gaseous fluid to be contacted is initially in the gaseous state itwill be introduced simply through an open ended pipe or through aconventional gas distributing nozzle. If the gaseous fluid to becontacted is initially a liquid which is easily and rapidly vaporizedupon contact with the solid, the nozzle 17 is preferably one which willatomize the liquid such, for example, as a swirl chamber atomizer.

By using a wider orifice the sheet may be made up to any desiredthickness. However, since the contact is so efficient it will rarely benecessary to have the sheet more than a few inches thick. 7

Greater throughput capacity may be obtained by in creasing the height ofthe sheet and by increasing the diameter of the cylinder, preferably thelatter. If the diameter of such a cylindrical sheet is greatlyincreased, e.g. to several feet, the space within the cylinder becomesrather large. In order to decrease the residence time of the gaseousfluid in this space an axially placed dummy of cylindrical or conicalshape somewhat smaller than the space may be provided. The gaseous fluidis thereby caused to occupy only that part of the space between thedummy and the sheet.

In this arrangement also one or more gaseous fluids may be suppliedeither separately or in admixture and contacted by passage through thesheet. Also, as in the arrangement shown in Figures 1 and 2, anadditional gaseous reactant may be supplied into the space (by means notshown) downstream with respect to the sheet ll; order to react this gaswith the gases issuing from the seet.

The quenching of the contacted gaseous fluid may be eifected asdescribed by injection of a suitable quenching liquid via line 14 intothe product line 13. The quenching may, however, be effected even morepromptly by passing the gaseous reactant product issuing from the sheetdirectly through a second sheet having a low temperature. A very rapidcooling of the gaseous fluid can thereby be effected immediatelyfollowing the rapid heating. Thus, an arrangement similar to thatillustrated in 'Figure 1 may be provided with a second sheet ofrelatively cold material as illustrated in Figures 5 and 6.

Referring to these figures the second sheet 18 is at a relatively shortdistance from the hot sheet 1. Cooled solid is supplied into anupperfluidized bed 20 by means of line 19. As before, the solid ismaintained in a wellfluidized state by the injection of a suitableaeration medium introduced by line 21. The orifice for this second sheetis the slit 22. This sheet is collected in the lower collecting device23 which is filled with the solid maintained in a fluidized state byinjection of a suitable aeration medium via line 24. The hot and coldfluidized materials are withdrawn from their respective collectingdevices by lines 7 and 25, respectively.

In a similar manner the hot and cold sheets may take the form of twoconcentric cylinders as illustrated in Figures 7 and 8. The gaseousfluid to be contacted is supplied at a point or points in the interiorof the inner sheet 16 through the nozzle 17. The gaseous fluid passesthrough this sheet whereby it is rapidly raised to a high temperatureafter which the hot gaseous product passes through the outer sheet 53whereby it is rapidly cooled.

In the arrangement illustrated in Figures 9 and 10, there are twosheets, both of which are relatively hot. This arrangement is suitablefor reacting gaseous fluids which have to be raised separately to therequired reaction temperature. Thus, one of the fluids is supplied onthe left of sheet 1 via the lines 10, 11, and 12 and the second gaseousfluid is supplied to the right of the sheet 1' via lines 26, 27 and 28.After these respective fluids pass through the sheets they react in thespace within vessel 3 which is defined by the two sheets. The reactionproduct is removed through line 29 either with or without quenching.

In the arrangement illustrated in (Figures 11 and 12,

H e. V there are likewise two hot-Isheets' 16 and 16* in the form ofconcentric cylinders. One of the. gaseous fluidsis introduced on theoutside of the outer-cylinder and passes inward. The other gaseous fluidis introduced invthe space within the inner r cylinder and passesoutward; The two pre-heated gaseous'reactants react in theannular spacebetweenthe two cylinders and are-withdrawn by line. 29. l I p I Figureliq shows an apparatus operating on the principle illustrated in Figure3. The"hot sheet 16 is supplied from the upper'fluidized'bed in chamberthrough an annular slit. The sheet is therefore in the form of acylinder. The solid material invesselS is maintained in the fluidizedstate by supplying'an aeration medium through line 9 the outlet of whichis positioned below the level of the slit 15. This arrangement insures aregular supply of thefluidized solid according 'to the laws for liquid.flo w. The sheet falls into the collecting device 6 in which a bed ofthe solids is maintained fluidized is spaced some distance from thesheet.

In'this particular. arrangement a baflle33'is provided which partlyextends into the fluidized -bed in the 1 can lecting device 6. The 'topof this bathe partly surrounds as the wall 32 leaving some space. c Inthe arrangementillustrated in Figure 14 the wall .32 is providedwith'louvers arranged in such a way? that the gas passing therethrough'is sharply deflected in an upward direction. As before, the wall 32' isspaced away. from the sheetso that the sheet falls free without wallfriction. n

In some cases a small amount of the finer particles of the solid arecarried with the efliuent gaseous fluid. Any

material so carried in suspension may be separated with.

a cyclone separator 35 insertedin the discharge line 13. The gaseousfluid from which any substantial solids have been separated is withdrawnthrough the overflow 36 and the solid particles whichhave beenseparated'flow by gravity down the dip leg of the cyclone'to the sealpot 37 from which they pass to .vessel'38r The fluidized solid in thecollecting device 6 likewise overflows into the lower vessel 38. A line39 leads from the vessel 38 to a heater (not shown) and a riser' (notshown) for transferring the solid particles from the level 'of thedischarge line 39 at least to the level of the inlet 4 'of the uppervessel 5. The solid in the lowervessel 38 is further stripped ofoccluded material and maintained in a fluidized state by the injectionof a suitable aeration medium. This material, as well as the aerationmedium supplied by line 8 to the disengaging device 6, is removed withthe product through line 13 and the cyclone over- The gaseous fluidremoved by line 36 after having been contacted with the solid usuallycontains some gaseous by-products of side reactions. While such sidereactions :are minimized by the use of the described method ofcontacting they usually cannotbe totally avoided. After removing thedesired product from the reaction mixture this residual gas may beadvantageously utilized to fluidize "the solid in the upper bed. Forthis purpose it may be "introduced by line 9.

The apparatus illustrated in Figure 13 was used for f th production oflight olefins by short time, high temhaving the followperature crackingof a heavy cyclic oil ing properties: 7

'Molecular weight 366 Normal paIaflins percent 35Isoparaffins-i-naphthenes do 63 'The above-mentioned sa'nd was used toform the screen which'w'as 5 centimeters internaldiaineter, 6.5 centimeacumen ters external diameter, and 25 centimeters in length.

@The nominal throughput of the sand was about 12 tons per hour.The'results are given in the following tabulation:

Temperature v C-.. 750 Hydrocarbon throughput lcg./hour 40 Residencetime (atomizer to quench) seconds 0.4 Conversion, weight percent on feed80.2 Ethylene yield,.weight percent on feed. 24.4 Methane yield; weightpercent on feed; 8.2

The same apparatus and sand were used for-the short contact time hightemperature cracking of a brights'tock slack wax at temperatures between750 and 850 C. and at a throughput rate of 40 kg./hour. The results aretabulated below'z' a Temperature, o r50 800 850 Residence time (atomizerto quench), seconds 0. 3 0.25 0. 2O Conversion, wt. percent on feed 76'84 Ethylene yield, wt. percent on teed 16; 5 26. 7 Methane yield, wt.percent on feed 5.2 9. 8

-. which are led from thecollecting device 6 of the apparatus A via theriser i0 and the cyclone 41 to the supply hopper 42' of part B.Fluidization medium is supplied through the line 43 to the fluidized bedin vessel 42. The discharge nozzle is again an annular slit 44 whichproduces a cylindrical sheet in vessel 45.

' Fuel is supplied by line 47 and nozzle 48 together with combustion airby line 49 into the space enclosed by the sheet. The combustion gasespass through the sheet thereby heating it and are withdrawn. throughline'fit) connected to vessel 45. If the solid contains carbonaceousmaterialthis may be partly or completely burned off through the use ofexcess air in the combustion mixture.

The collecting device 51 of the apparatus B for the hot material'isprovided with a supply line 52 for fluidization medium and at the sametime forms the supply for the lower sheet 16 in apparatus A. The gaseousfluid to' be contacted is introduced, as before, by nozzle 17 and thecontacted product is removed by line 13. In this arrangement it will benoted that the sheet is housed for substantially its entire lengthwithout frictional contact by the depending baflle member 32. Thisbaffle extends to within a short distance above the level of thefluidized bed of material in the collecting device 6. The material ofthe sheet 16 is collected in the fluidized bed in the collecting device6 from which it is withdrawn by line 7 to a riser 4% wherein it iscarried to the cyclone 41 and from there back to the supply chamber 42ofthe part B.

The apparatus shown in Figure 16 is similar to that shown in Figure 13but differs in the arrangement of the collecting device and baflleshielding around the sheet.

The solid collected in the lower fluidized bed in vessel 38 passes byline 39 to the lift pot at the bottom of a vertical 7 riser wherein itis elevated to a point above the level of the discharge passage 4. Airintroduced at the bottom of the lift pot serves as the conveying medium.The solid is separated from the air by an exceedingly simple but 1efiectiveiseparator consisting of the large inverted hat placed directlyabove the exit of thevertical riser line.

better control the temperature at which the reaction occurs, and/or tolimit the time at such temperature.

As explained above, the processes and apparatuses of the invention areparticularly suitable for the thermal cracking of paraflin waxes toproduce olefins. This cracking is preferably carried out at-temperaturesof the order of 700800 C. in the presence of steam, and in some casesoxygen. They also are suitable for the reaction of methane with steam toproduce carbon monoxide and hydrogen. Oxidation reactions such as thereaction of methane with oxygen under conditions to produce acetylene oraromatic hydrocarbons can be also carried out in the manner indicated.Another application is in the oxidation of ammonia at temperatures ofthe order of 700-100 C.

Also, various catalytic processes may be carried out such as thedehydrogenation of alkanes to alkenes using a chromium oxide catalyst orone of the various other known dehydrogenation catalysts.

In the chlorination of propylene to produce allyl chloride it is highlydesirable to eifect the reaction at a high temperature, e.g. above 500C., with a very short contact time. The present method and apparatus aresuitable for this type of reaction. The reaction between methane,ammonia, and oxygen to produce hydrogen cyanide and water using acatalyst containing platinum can also be efiected, as also the reactionof methane and nitrogen oxide to produce hydrogen cyanide atapproximately 1000 C..

The rate at which heat is transmitted when operating according to themethod'of the invention is very large. By way of example a heattransmission of 3 X10 KCal. per cubic meter of treating space per hourhas been obtained in the apparatus illustrated in Figure 13. The solidmaterial in this case was the above mentioned silica sand. Thecylindrical sheet in this case had an annular cross section with aninternal diameter of 5 centimeters, an external diameter of 6.5centimeters and a height of 30 centimeters. The mass velocity of sand inthis sheet was tons per hour. The temperature of the sand in thefluidized bed in chamber 5 was 750 C. Temperature of sand in thecollecting device 6 was 700 C. The residence time of the gaseous fluidwithin the cylinder which had a capacity of 3 liters was .03 second. Inpassing through the sheet the temperature of the gaseous fluid wasraised from 100 C. to 685 C. in 0.004 second.

I claim as my invention:

1. Process for effecting rapid change in temperature of a gaseous fluidin which the gaseous fluid is contacted with a fluidizable solid bypassing the said gaseous fluid transversely through a free fallingcoherent sheet of fluidizable solid formed by passing the solid from awell fluidized body of the solid through an unrestricted slitlikeorifice into a free fall space, said solid having a temperature whichvaries considerably from that of the said gaseous fluid to be contacted.

2. Process for efiecting rapid but intimate contact between a gaseousfluid and a fluidizable solid which comprises forming a well fluidizedbed of said solid, flowing said fluidized solid from said bed through aslit-like orifice into a free fall space to thereby create a coherentsheet of the free falling solid and passing the'gaseous fluid to becontacted transversely through said sheet.

3. Process according to claim 1 further characterized in that thegaseous fluid consists essentially of hydrocarbons and the temperatureof the sheet is sufiiciently high that the hydrocarbons are cracked inpassing through said sheet.

4. Process according to claim 1 further characterized in that saidgaseous fluid consists essentially of at least 2 reactants and that thetemperature of the sheet is so chosen that reaction between thereactants takes place during passage of the reactants through saidsheet.

5. Process according to claim 1 furthercharacterized 12 in that saidfluidized solid is a powder which is inert chemically and catalyticallywith respect to the gaseous fluid with which it is contacted.

6. Process according to claim 1 further characterized in that saidfluidized solid is at least in part formed of powdered substances whichcatalyze reactions which take place during passage of gaseous fluidthrough the sheet.

7. Process according to claim 1 further characterized in that thegaseous fluid contains at least 2 reactants which are allowed to reactafter being brought to the desired reaction temperature by contact withsaid sheet.

8. Process according to claim 2 wherein said sheet is in the form of acylinder and the gaseous fluid to be contacted is introduced within thecylinder.

9. Process according to claim 2 further characterized in that there aretwo said fluidized beds and two said sheets, one of which is maintainedat a high temperature and the other at a low temperature and that thegaseous fluid is passed serially through said sheets thereby providing avery short and substantially square temperature versus time curve.

10. Process according to claim 2 further characterized in that the saidslit-like orifice is substantially of plate thickness, is at least 5millimeters in width, and is positioned above the level of the point ofintroduction of fluidization gas in said fluidized bed.

11. An apparatus for eifecting a'rapid change in the temperature of agaseous fluid which comprises a first upper vessel adapted to maintain abed of fluidizable solid, gas distributing means in the lower part ofsaid vessel for the introduction of a fiuidizing gas to maintain saidsolid in a well fluidized condition, a slit-like orifice in the lowerpart of saidvessel but above the level of said distributing means, saidslit-like orifice being directly above a free fall space surrounded by awall of a lower chamber below and connected to said first vessel, asecond open-topped vessel positioned directly and at some distance belowsaid slit-like orifice, gas distributing means in the lower part of saidsecond vessel for maintaining the; contents thereof in a fluidizedcondition, a third and lower vessel larger and encompassing said secondvessel and sealed to said wall of said lower chamber and adapted tocatch the overflow of said second vessel, gas distribution means forinjecting fluidization gas into the lower part of said third vessel,means for injecting a gaseous fluid into said lower chamber on one sideof said slit-like orifice and means for withdrawing contacted gaseousfluid from said lower chamber on the other side of said slit-likeorifice.

12. Apparatus according to claim 11 further characterized in that saidapparatus is provided with an openended shield extending from said firstvessel and spaced a short horizontal distance from said orifice saidshield being within said lower chamber and extending from said firstvessel to a short distance above the top of said second vessel.

13. Apparatus according to claim 12 further characterized in that theapparatus is also provided with a cylindrical bafile open at both endsand positioned below said orifice at a greater horizontal distance fromsaid orifice than the said shield, said baflie extending in height fromabout the. lower end of said shield to a point within and somewhat belowthe eflective top of said second vessel.

14. Process for effecting rapid but intimate contact between a gaseousfluid and a fluidized solid which comprises forming a well fluidized bedof said solid, flowing 7 said fluidized solid from said bed through aslit-like aperture having a minimum confined channel with substantiallyno constricting hydraulic radius into a free fall space to therebycreate a coherent sheet of free falling solid and passing the gaseousfluid to be contacted transversely through said sheet.

15. Process according to claim 14 wherein the coherent sheet is shieldedover a substantial part of its height by a baffle on the side of thesheet through which the contacted gaseous fluid emerges and at adistance from the sheet of about 2 to 10 times the thickness of thesheet.

16. Process for eifecting rapid but, intimate contact between a gaseousfluid and a fluidized solid which com- 14 to create a coherent sheet ofthe fluidized free falling solid and passing thegaseous fluid to becontacted transversely through the sheet, said sheet extending acrossprises forming a well fluidized bed of said solid, flowing saidfluidized solid from said bed through a slit-like orifice into a freefall space at a mass flow rate suflicient to create a coherent sheet ofthe fluidized free falling solid and passing the gaseous fluid to becontacted transversely through the sheet, said sheet terminating at itslower end in a second fluidized bed of the solid and having itstransverse cross-section in the form of a closed figure.

17. Process for eflecting rapid but intimate contact between a gaseousfluid and a fluidized solid which comprises forming a well fluidized bedof said solid, flowing said fluidized solid from said bed through aslit-like orifice into a free fall space at a mass flow rate sufficientthe entire section of the confining chamber from wall to wall andterminating at its lower end in a second fluidized bed of solid.

References Cited in the file of this patent UNITED STATES PATENTS1,836,325 James Dec. 15, 1931 2,259,487 Payne Oct. 21, 1941 2,347,747Melaven c May 2, 1944 2,440,525 Roetheli Apr. 27, 1948 2,458,357 EvansJan. 4, '1949 2,542,887 Watson Feb. 20, 1951 2,574,850 Utterback et a1Nov. 13, 1951 2,697,686 Leflier Dec. 21, 1954 2,726,938 Lassiat Dec. 13,1955 Letter Mar. 12, 1957

1. PROCESS FOR EFFECTING RAPID CHANGE IN TEMPERATURE OF GASEOUS FLUID INWHICH THE GASEOUS FLUID IS CONTACTED WITH A FLUIDIZABLE SOLID BY PASSINGTHE SAID GASEOUS FLUID TRANSVERSELY THROUGH A FREE FALLING COHERENTSHEET OF FLUIDIZABLE SOLID FORMED BY PASSING THE SOLID FROM A WELLFLUIDIZED BODY OF THE SOLID THROUGH AN UNRESTRICTED SLITLIKE ORIFICEINTO A FREE FALL SPACE, SAID SOLID HAVING A TEMPERATURE WHICH VARIESCONSIDERABLY FROM THAT OF THE SAID GASEOUS FLUID TO BE CONTACTED.